Thermoplastic sheet forming apparatus and method

ABSTRACT

There are provided apparatuses and related methods for forming sheets. The formed sheets can be formed of a thermoplastic material, such as flat sheets of reinforced thermoplastic, which can be lightweight, strong, and perform well in flammability, smoke, and toxicity tests. The apparatus includes a heater for heating the sheet to a processing temperature and a structure for configuring the sheet to a desired shape using one or more rollers, shapers, longitudinal members, and/or support members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending U.S. patentapplication Ser. No. 10/215,815, filed on Aug. 9, 2002, which is herebyincorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to apparatuses and methods for formingthermoplastic materials and, more specifically, to apparatuses andmethods for bending thermoplastic sheets to form ducts, channels, arcs,spirals, and the like.

2) Description of Related Art

Longitudinal passages such as ducts, channels, arcs, spirals, and thelike are used to provide passageways for a wide variety of applications.For example, tubular ducts are widely used for air flow in aircraftenvironmental control systems. Similarly, ducts provide passageways fortransporting gases for heating and ventilation in other vehicles and inbuildings. Water distribution systems, hydraulic systems, and otherfluid networks also often use ducts for fluid transport. In addition,solid materials, for example, in particulate form can be deliveredthrough ducts and channels. A variety of longitudinal shapes can also beused as conduits in which electrical wires or other components areplaced. Such longitudinal passages for the foregoing and otherapplications can be formed of metals, plastics, ceramics, composites,and other materials.

One conventional aircraft environmental control system utilizes anetwork of ducts to provide air for heating, cooling, ventilation,filtering, humidity control, and/or pressure control of the cabin. Inthis conventional system, the ducts are formed of a composite materialthat includes a thermoset matrix that impregnates, and is reinforced by,a reinforcing material such as Kevlar®, registered trademark of E.I. duPont de Nemours and Company. The thermoset matrix is typically formed ofan epoxy or polyester resin, which hardens when it is subjected to heatand pressure. Ducts formed of this composite material are generallystrong and lightweight, as required in many aircraft applications.However, the manufacturing process can be complicated, lengthy, andexpensive, especially for ducts that include contours or features suchas beads and bells. For example, in one conventional manufacturingprocess, ducts are formed by forming a disposable plaster mandrel,laying plies of fabric preimpregnated with the thermoset material on themandrel, and consolidating and curing the plies to form the duct. Thetools used to mold the plaster mandrel are specially sized and shapedfor creating a duct of specific dimensions, so numerous such tools mustbe produced and maintained for manufacturing different ducts. Theplaster mandrel is formed and destroyed during the manufacture of oneduct, requiring time for curing and resulting in plaster that typicallymust be removed or destroyed as waste. Additionally, the preimpregnatedplies change shape during curing and consolidation and, therefore,typically must be trimmed after curing to achieve the desireddimensions. The jigs required for trimming and for locating the properpositions for features such as holes and spuds are also typically usedfor only a duct of particular dimensions, so numerous jigs are requiredif different ducts are to be formed. Like the tools used for forming themandrels, the jigs require time and expense for manufacture, storage,and maintenance. Additionally, ducts formed of conventional thermosetepoxies typically do not perform well in certain flammability, smoke,and toxicity tests, and the use of such materials can be unacceptable ifperformance requirements are strict. Further, features such as beadstypically must be post-formed, or added after the formation of the duct,requiring additional manufacture time and labor.

Alternatively, ducts can be formed of thermoplastic materials. Athermoplastic duct can be manufactured by cutting a sheet ofthermoplastic material to a size and shape that corresponds to thedesired dimensions of the duct, bending the sheet to the desiredconfiguration, and joining longitudinal edges of the sheet to form alongitudinal joint or seam. For example, apparatuses and methods forforming thermoplastic ducts and consolidation joining of thermoplasticducts are provided in U.S. application Ser. Nos. 10/216,110 and10/215,833, titled “Thermoplastic Laminate Duct” and “ConsolidationJoining of Thermoplastic Laminate Ducts,” both filed on Aug. 9, 2002 andassigned to the Assignee of the present invention. Such thermoplasticducts can be formed by retaining the thermoplastic sheet in the bentconfiguration until the ends are joined, and then releasing the duct sothat the resulting joint continues to restrain the duct in the bentconfiguration. However, stresses induced in the thermoplastic materialduring bending can cause the duct to deform or distort from the desiredconfiguration after joining, e.g., when released from the joiningapparatus.

Thus, there exists a need for improved apparatuses and methods forforming a thermoplastic sheet to correspond generally to a desiredconfiguration in a substantially unstressed condition. The method shouldnot require the laying of individual plies on a disposable plastermandrel. Preferably, the method should be compatible with thermoplasticducts, including reinforced thermoplastic ducts formed from flat sheets,which provide high strength-to-weight ratios and meet strictflammability, smoke, and toxicity standards.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method for formingsheets to desired configurations. The sheets can be formed to thedesired configuration of a finished shape such as an arc, channel, orspiral. Alternatively, each sheet can be formed as a preform thatgenerally corresponds to the desired configuration of a finished shapesuch as a duct and is subsequently joined to form the finished shape.Joining can be accomplished by consolidation joining. The sheets can beformed from thermoplastic materials, such as flat sheets of reinforcedthermoplastic laminate that are lightweight, strong, and perform well inflammability, smoke, and toxicity tests.

According to one embodiment of the present invention, the apparatusincludes a rotatable roller, an elastically flexible shaper, and aheater. The apparatus can be used to hold the sheet in a predeterminedconfiguration while the heater is used to heat the sheet. The shaperreceives the thermoplastic sheet on one side so that rotation of theroller advances the shaper around the roller to bend the thermoplasticsheet. An index feature can be provided on the shaper for engaging thethermoplastic sheet so that the adjustment of the index feature towardthe roller advances the thermoplastic sheet around the roller. Theapparatus can also include a second shaper that is disposed on thethermoplastic sheet so that the second shaper is bent between the sheetand the roller and advancement of the second shaper toward the rollerurges the thermoplastic sheet radially outward from the roller.Longitudinal members can be configured to adjust radially toward theroller to bend the thermoplastic sheet to a predetermined configuration.

According to another embodiment of the present invention, the apparatusincludes at least two support members that extend, for example, in alongitudinal direction, to define at least one space therebetween. Ashaper is configured to be disposed with one side against the supportmembers so that the shaper extends across the at least one space. Theshaper receives the thermoplastic sheet on a side opposite the supportmembers and bends partially around the members, which can be adjustable.A heater is configured to heat the thermoplastic sheet to a processingtemperature less than a glass transition temperature of thethermoplastic member and within about 70° F. of the glass transitiontemperature.

The present invention also provides a method of forming a thermoplasticsheet. According to one embodiment of the present invention, thethermoplastic sheet is disposed on a first side of a shaper. Alongitudinal roller connected to the shaper is then rotated, forexample, by at least one revolution, to advance the shapercircumferentially around the roller so that the thermoplastic sheet isdisposed between the roller and the shaper and bent to a predeterminedshape. Longitudinal members can be radially adjusted toward the rollerto bend the thermoplastic sheet to a predetermined configuration. Theshaper can be advanced toward the roller so that the shaper adjustsradially outward from the roller to define a maximum size for thethermoplastic sheet, for example, so that an index feature of the shaperengages the sheet and adjusts the sheet radially outward from theroller. According to one aspect, a second shaper is disposed on thesheet so that the second shaper is advanced around the roller betweenthe sheet and the roller. The second shaper can be adjusted radiallyoutward from the roller to urge the thermoplastic sheet to apredetermined configuration. The thermoplastic sheet is heated to aprocessing temperature, for example, within about 70° F. of a glasstransition temperature of the thermoplastic sheet. The thermoplasticsheet can be cooled in the apparatus to a temperature below about 70° F.less than the glass transition temperature before the sheet is removed.

According to another embodiment of the present invention, at least twosupport members are provided with a space therebetween. A shaper isdisposed on the support members so that the shaper extends across thespace and bends partially around the support members to a predeterminedshape. A thermoplastic sheet is disposed on the shaper and heated to aprocessing temperature. The thermoplastic sheet can be cooled to atemperature below about 70° F. less than the glass transitiontemperature of the thermoplastic sheet while the thermoplastic sheet andthe shaper are disposed on the support members. The support members canbe adjustable. According to one aspect, a second shaper can be disposedon the thermoplastic sheet opposite the first shaper and some of thesupport members can be adjusted in a direction toward the sheet so thatthe sheet is bent between the support members.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is a perspective view illustrating a forming apparatus accordingto one embodiment of the present invention;

FIG. 2 is a perspective view illustrating a formed sheet according toone embodiment of the present invention;

FIG. 2A is a perspective view illustrating a formed sheet according toanother embodiment of the present invention;

FIG. 3 is a section view illustrating the forming apparatus of FIG. 1,shown with the shaper in a first position;

FIG. 4 is a section view illustrating the forming apparatus of FIG. 1,shown with the shaper advanced to a second position;

FIG. 5 is a section view illustrating a forming apparatus according toanother embodiment of the present invention, shown with a second shaperdisposed on the sheet and both shapers advanced to the second position;

FIG. 6 is a section view illustrating a forming apparatus according toanother embodiment of the present invention, shown with the shaper in afirst position and with longitudinal members in a first position;

FIG. 7 is a section view illustrating the forming apparatus of FIG. 6,shown with the shaper in a second position and with the longitudinalmembers in a second position;

FIG. 8 is a perspective view illustrating a forming apparatus accordingto another embodiment of the present invention;

FIG. 9 is a section view illustrating the forming apparatus of FIG. 8,shown with a thermoplastic sheet and a shaper disposed on the supportmembers;

FIG. 10 is a section view illustrating a forming apparatus with a secondset of support members, according to another embodiment of the presentinvention; and

FIG. 11 is a perspective view illustrating a forming apparatus accordingto another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring now to FIG. 1, there is shown a forming apparatus 10 forforming a formed sheet 60, such as the one shown in FIG. 2, from athermoplastic member, such as a thermoplastic sheet 50. Forminggenerally refers to bending the thermoplastic member to a bent or curvedconfiguration and processing the member, for example, using heat, sothat the member generally remains in a desired configuration whenunrestrained. The formed sheet 60 can be a finished shape, such as anarc, spiral, channel, and the like. Alternatively, the formed sheet 60can be used as a preform, i.e., a formed shape that is joined orotherwise processed to form a finished shape and remains in the desiredconfiguration when unrestrained. For example, the flat sheet 50 can bebent and heated to form the cylindrical formed sheet 60, shown in FIG.2, which extends from a first end 62 to a second end 64 and defines apassage 66. Longitudinal edges 68, 70 of the formed sheet 60 can definea gap therebetween, can be overlapped, or can be joined to form a seamor joint. If used as a preform, the longitudinal edges 68, 70 of theformed sheet 60 can be joined to form a duct which, when unrestrained,defines a partially closed cylindrical shape. The preform can be formedto have a diameter slightly larger or smaller than the desired diameterof the duct. Thereafter, the formed sheet 60 can be subjected to acompressive or expansion force for holding the formed sheet duringsubsequent processing, such as joining, to arrive at the desiredconfiguration of the duct. The longitudinal edges 68, 70, or otherportions of the formed sheet 60, can be joined using adhesives, heat, orother joining methods. For example, joining can be achieved by applyingheat and pressure to the edges 68, 70 to form the seam. As thethermoplastic material of the formed sheet 60 is heated above its glasstransition temperature, the material becomes plastic and the pressureconsolidates and joins the interface. Joining can be performed by manualor automated methods, for example, as described in U.S. application Ser.No. 10/215,833, titled “Consolidation Joining of Thermoplastic LaminateDucts,” the entirety of which is incorporated herein by reference. Thus,as used throughout this application, the term “formed sheet” refersgenerally to a sheet that has been formed to a curved or bentconfiguration, including sheets that are formed to a final desiredconfiguration without joining, preforms that require joining or otherprocessing to achieve the final configuration, and partially closedshapes that are formed by joining such preforms.

The shape of the formed sheet 60 is determined by projecting the desiredshape of the formed sheet 60 onto the flat sheet 50. Although the ends62, 64 and edges 68, 70 of the formed sheet 60 are shown to be straightand parallel in FIG. 2, the formed sheet 60 can alternatively bestraight, curved, tapered, or otherwise contoured. For example, there isshown in FIG. 2A an alternative formed sheet 60, which defines anon-uniform, or transitional, radius that tapers between the ends 62,64. The sheet 50 and, hence, the formed sheet 60 can also define avariety of features such as holes, for example, for connecting spuds,brackets, and the like to the formed sheet 60. Methods and apparatusesfor forming sheets and for determining geometric patterns thatcorrespond to ducts are provided in U.S. application Ser. No.10/216,110, titled “Thermoplastic Laminate Duct,” the entirety of whichis incorporated herein by reference. It is also appreciated that markscan be provided on the formed sheet 60, for example, to accuratelyidentify the location of post-formed features such as beads, bells, andassembly details or to facilitate the manufacture or assembly of theformed sheet 60, as also provided in the application entitled“Thermoplastic Laminate Duct.”

Preferably, the formed sheet 60 is formed of a thermoplastic sheet or ofa composite laminate that includes a thermoplastic matrix and areinforcing material. Thermoplastic materials are characterized by atransition to a plastic state when heated above a glass transitiontemperature. For example, the formed sheet 60 can be formed ofpolyetherimide (PEI) or polyphenol sulfide (PPS), both of which can bethermoplastic. Thermoplastic PEI is available under the trade nameUltem®, a registered trademark of General Electric Company. According toone embodiment of the present invention, each formed sheet 60 iscomprised of a composite material that includes a matrix ofthermoplastic PEI that is reinforced with a reinforcing material such ascarbon, glass, or an aramid fabric such as a Kevlar® aramid, or fibersof such a material. Alternatively, the formed sheet 60 can be formed ofother thermoplastic materials, which can be reinforced by otherreinforcing materials, or can include no reinforcing materials.

The formed sheet 60 can be used in numerous applications including, butnot limited to, environmental control systems of aerospace vehicles. Forexample, the formed sheet 60 can be used as a preform that is used toform a duct, as described above. The resulting duct can be used as apassage in a system though which air is delivered to provide heating,cooling, ventilation, and/or pressurization of an aircraft cabin.Alternatively, the formed sheet 60 can be used without furtherprocessing, for example, as a channel or conduit for wires or cables.The ends of the formed sheet 60 can be connected to other channels,ducts, tubes, formed sheets, or other devices such as ventilators,compressors, filters, and the like. Multiple formed sheets 60 can beconnected so that a longitudinal axis of each formed sheet 60 isconfigured at an angle relative to the longitudinal axis of theadjoining formed sheet(s). Thus, the formed sheet 60 can be connected toform an intricate passage system (not shown) that includes numerousangled or curved passages for accommodating the various devicesconnected by the passage system and for meeting layout restrictions asrequired, for example, on an aircraft where space is limited. Inaddition, formed sheets according to the present invention can be usedto form barriers or walls that are used to separate lighted areas fromdarker areas, people from secure areas, or cold from warm areas.Further, the formed sheets can provide visual barriers.

The forming apparatus 10 shown in FIG. 1 includes a roller 12 and ashaper 14, both of which are provided on a frame 16. The roller 12extends longitudinally and is supported by the frame 16 such that theroller 12 is rotatable. The roller 12 can be at least partiallysurrounded by an insulative heat shroud 18, which extends parallel tothe roller 12 and facilitates the heating of a space 20 within theshroud 18 by a heater 22. The heater 22 can be any of various types ofheaters such as electric and gas heaters, and can be positioned oneither end of the shroud 18 or along the longitudinal length of theshroud 18. The heater 22 can be configured to heat the sheet 50 throughthe shroud 18 or by heating air that is blown into the space 20 withinthe shroud 18. Alternatively, the apparatus 10 can be used without theshroud 18, and the heater 22 can be configured to heat the space aroundthe roller 12. The roller 12 can also be heated directly by a heater,for example, by an electric heater disposed within the roller 12.

The shaper 14 is an elastically flexible laminar sheet, i.e., a sheetthat can be bent from its initial configuration during forming withoutundergoing any appreciable plastic deformation so that the shaper 14 canreturn to its initial configuration after processing and can be re-used.The shaper 14 can be formed of a variety of materials, including, forexample, a sheet of stainless steel which is about 0.015 inches thick.In the illustrated embodiment, the shaper 14 is configured so that afirst edge 24 is parallel to the roller 12 and connected to the roller12, though in other embodiments, the first edge 24 can be oriented inother configurations and need not be connected to the roller 12. Theshaper 14 is slidably adjustable relative to the roller 12 so that asecond edge 26 of the shaper 14 opposite the first edge 24 is adjustablebetween first and second positions. In the first position, the shaper 14extends from the roller 12 as shown in FIGS. 1 and 3. In the secondposition, the second edge 26 of the shaper 14 is adjusted toward theroller 12 and the shaper 14 is at least partially bent around the roller12, as shown in FIG. 4. The shaper 14 can engage tracks 17 or otherfeatures provided on the frame 16, which maintain the second edge in aparallel arrangement with the roller 12. By the term “advanced” it isgenerally meant that a portion of the shaper 14 that is not bent aroundthe roller 12 is adjusted toward the roller 12 to increase the portionof the shaper 14 that is bent around the roller 12, for example, byincreasing the diameter of the portion bent around the roller 12 or byfurther extending the shaper 14 circumferentially around the roller 12.If the apparatus 10 is configured as shown in FIGS. 3 and 4, the shaper14 can be advanced by adjusting the second edge 26 toward the roller 12.

Adjustment of the shaper 14 to the second position can be accomplishedby rotating the roller 12 in a first direction, clockwise as shown inFIGS. 3 and 4, so that the first edge 24 of the shaper 14 rotates aroundat least part of the roller 12, the shaper 14 bends, and the second edge26 of the shaper 14 is advanced toward the roller 12. As the roller 12is rotated in a second direction, counterclockwise in FIGS. 3 and 4, theshaper 14 unrolls from the roller 12 and the second edge 26 is retractedfrom the roller 12. The roller 12 can be actuated by an automated devicesuch as an electric motor or the roller can be manually actuated, forexample, by a crank 13 that is rotated by an operator. Alternatively,the roller 12 can be configured to rotate freely so that the shaper 14can be advanced toward the roller 12, either manually or by an actuator,thereby rotating the roller 12 and rolling the shaper 14 around theroller 12. In another embodiment, the first edge 24 of the shaper 14 isnot connected to the roller 12, and the shaper 14 can be advanced intothe shroud 18 so that the shaper 14 bends around the roller 12, whichcan remain stationary. In either case, the second edge 26 of the shaper14 can be adjusted relative to the roller 12 while the roller 12 is heldin place so that a portion of the shaper 14 that is disposed around theroller 12 is adjusted radially outward from the roller 12 to a desiredconfiguration, generally defining a maximum circumference of the sheet50, as described further below.

The extent to which the shaper 14 is rolled around the roller 12 can bedetermined according to the desired shape of the formed sheet 60. Forexample, the shaper 14 and thermoplastic sheet 50 can be advancedslightly more than one revolution around the roller 12 so that theresulting formed sheet 60 defines a generally cylindrical shape withoverlapping longitudinal edges that can be joined to form a tubularduct. Alternatively, the sheet 50 can be rotated less than onerevolution around the roller 12 to form an arc or, channel, or spiral,or the sheet 50 can be rotated more than one revolution to form a spiralshape.

During operation, the thermoplastic sheet 50 is disposed on the shaper14 as shown in FIG. 1 so that the sheet 50 is rolled around the roller12 between the shaper 14 and the roller 12. While the sheet 50 issupported between the shaper 14 and the roller 12, the heater 22 can beused to heat the sheet 50, e.g., by connecting a power supply (notshown) to the heater 22 and energizing the heater 22. Preferably, thesheet 50 is heated to a processing temperature that is less than theglass transition temperature of the thermoplastic material of the sheet50. For example, the processing temperature can be between about 5° F.and 70° F. less than the glass transition temperature. In the case ofPEI, which has a glass transition temperature of about 417° F., thesheet 50 can be heated to a processing temperature of between about 347°F. and 412° F. The sheet 50 can be maintained at the processingtemperature for a predetermined period, such as about 10 minutes, afterwhich the heater 22 can be turned off and the formed sheet 60 ispreferably at least partially cooled in the apparatus 10. The formedsheet 60 can be removed from the apparatus 10 through openings 28, 30 atthe longitudinal ends of the heat shroud 18, or the heat shroud 18 canbe configured to disassemble or otherwise open to facilitate the removalof the formed sheet 60. Alternatively, the formed sheet 60 can beremoved by reversing the load process, i.e., unwinding the formed sheet60 from the heat shroud 18 in a direction opposite to the direction inwhich the sheet 50 is inserted so that the formed sheet 60 unwindsaround the outside of the heat shroud 18.

The thermoplastic sheet 50 can be a precut sheet that corresponds to thedesired dimensions of the formed sheet 60 so that the formed sheet 60 istrimmed only slightly or not at all after processing in the apparatus10. Alternatively, the thermoplastic sheet 50 can be part of a longcontinuous sheet, such as a roll of thermoplastic laminar material, andthe sheet 50 can be cut during or after processing. In either case, theshaper 14 can include an index feature that engages a portion of thesheet 50 so that the adjustment of the sheet 50 into the apparatus 10can be easily controlled and/or measured. For example, the shaper 14 caninclude a gate 32 at the second edge 26, as shown in FIGS. 1, 3, and 4.The sheet 50 can be disposed on the shaper 14 so that an edge of thesheet 50 rests against the gate 32, and the gate 32 prevents the sheet50 from slipping relative to the shaper 14 when the shaper 14 isadvanced around the roller 12.

According to one embodiment of the present invention, the sheet 50 isdisposed on the shaper 14, and the roller 12 is rotated through apredetermined angle of rotation. The roller 12 can be rotated using theactuator or crank 13, or the second edge 26 of the shaper 14 can beurged toward the roller 12 to rotate the roller 12. The roller 12 isthen held at the desired rotational position while the second edge 26 ofthe shaper 14 is adjusted toward or away from the roller 12 to increaseor decrease the diameter of a generally cylindrical portion of theshaper 14 bent around the roller 12. By keeping the second edge 26parallel to the first edge 24, a constant radius can be imparted to theformed sheet 60. Alternatively, the second edge 26 can be positioned ina non-parallel, or skewed, relationship relative to the first edge 24 sothat a non-uniform, or transitional radius, is imparted to the formedsheet 60, i.e., the radius at one end 66 is different than the other end64 of the formed sheet 60.

The shaper 14 also adjusts the sheet 50 to a desired configuration. Forexample, the sheet 50 can be engaged by the gate 32, and the gate 32 canbe adjusted toward the roller 12 so that substantially all of the sheet50 is bent around the roller 12. Thus, if the sheet 50 is long enough toextend substantially from the first edge 24 of the shaper 14 to the gate32, the sheet 50 will be disposed against the shaper 14 when the shaper14 is bent around the roller 12. The length of the sheet 50 can beselected according to the desired size of the finished shape, and thegate 32 can be adjustable on the shaper 14 so that the shaper 14 can beused for sheets 50 of different lengths, the length of each sheet 50generally determining the circumferential size of the formed sheet 60.If the sheet 50 is longer than the circumference of the formed sheet 60,the formed sheet 60 can be trimmed after forming.

A second shaper 34 similar to the first shaper 14 can also be disposedon the thermoplastic sheet 50 so that the second shaper 34 is rolledaround the roller 12 between the sheet 50 and the roller 12, as shown inFIG. 5. The second shaper 34 can be slidably adjustable toward theroller 12, as described above in connection with the first shaper 14.Thus, the first shaper 14 can be advanced a predetermined distancetoward the roller 12 to define a maximum outer dimension of the formedsheet 60, and the second shaper 34 can be advanced a predetermineddistance toward the roller 12 to urge the sheet 50 radially outwardtoward the first shaper 14. The shapers 14, 34 can be adjusted radiallyoutward by advancing the rollers 14, 34 after the roller 12 has beenrotated to a desired position and held in that position. Alternatively,the shapers 14, 34 can be adjusted radially outward by advancing theshapers 14, 34 while the roller 12 is being rotated, the shapers 14, 34being advanced at a rate faster than the speed of a periphery of theroller 12. The second shaper 34 can be connected to the roller 12 or thefirst shaper 14, or the second shaper 34 can be connected to neither. Inthe illustrated embodiment, however, the second shaper 34 is alsoattached to the roller 12, albeit at a location spaced circumferentiallyfrom the location at which the first shaper 14 is attached to the roller12 so that the sheet 50 may be disposed therebetween. Additionally, thesecond shaper 34 can have a gate 35 or other index feature for engagingthe sheet 50. As shown, for example, the gate 35 of the second shaper 34may extend toward the first shaper 14 such that the sheet 50 is retainedtherebetween.

In another embodiment of the present invention, the apparatus 10includes one or more radially adjustable members 40, as shown in FIGS. 6and 7. Each member 40 can be a longitudinal member such as a rod, ashoe, or the like that extends generally parallel to the roller 12. Themembers 40 are configured to be adjusted relative to the roller 12 toprovide support to the shaper 14 and the sheet 50. The members 40 can beadjusted to a first position, shown in FIG. 6, so that the members 40 donot interfere with the entry and bending of the shaper 14 and sheet 50around the roller 12. The members 40 can then be adjusted toward theroller 12 to bias the shaper 14 and the sheet 50 to a particularconfiguration. For example, if the shaper 14 and sheet 50 do notmaintain a cylindrical shape when bent around the roller 12, the members40 can be actuated radially inwards, as shown in FIG. 7, to engage theshaper 14 and urge the shaper 14 to the desired configuration. Themembers 40 can also be used to bend the shaper 14 to other shapes,including shapes with flattened portions or complex curves. Any numberof members 40 can be provided in the apparatus 10, and the members 40need not be straight or extend the entire length of the apparatus 10.Further, the members 40 can be positioned within the shaper 14, i.e.,between the sheet 50 and the roller 12, so that the members 40 can beactuated outward toward the sheet 50 and shaper 14.

FIGS. 8 and 9 illustrate an alternative forming apparatus 110 in which ashaper 114, similar to the shaper 14 described above, is supported on aplurality of support members 140 that are supported by a frame 116. Thesupport members 140 can be longitudinal members such as rods or othershapes that are arranged in a generally parallel configuration, as shownin FIG. 8, so that the members 140 define spaces 142 therebetween. Inother embodiments, the support members 140 can be arranged in otherconfigurations, in which the support members 140 need not be parallel. Aheater 122 can be provided within each member 140 or elsewhere in theapparatus 110, and the apparatus 110 can be partially or completelyenclosed by an insulative shroud 118. The thermoplastic sheet 50 isdisposed on a first side of the shaper 114, and a second side of theshaper 114 is disposed against the members 140 so that the shaper 114extends across the spaces 142 between the members 140 and so that thesheet 50 can bend between the members 140, as shown in FIG. 9. Theshaper 114 and the sheet 50 can be bent by gravity, or opposing supportmembers 144 can be provided, as shown in FIG. 10, for urging the sheet50 to a desired configuration. A second shaper 134 can also be providedon the sheet 50 opposite the first shaper 114, as shown in FIG. 10,i.e., between the sheet 50 and the members 144.

Each of the members 140, 144 can be adjustable in position, for example,in a direction transverse to the longitudinal direction of the members140, 144. Thus, as shown in FIG. 10, each of the members 140, 144 can beadjusted in any direction to determine the shape of the formed sheet 60.The members 140, 144 can be mounted on tracks or other adjustablesupporting devices, and each member 140, 144 can be adjusted manually,or actuators can be provided for such adjustment. For example, FIG. 10illustrates a plurality of actuators 146, each of which is configured toextend or retract a respective one of the members 140, 144 toward oraway from the sheet 50.

During one typical method of operation, the shaper 114 is disposed onthe members 140, the sheet 50 is disposed on the shaper 114, the secondshaper 134 is disposed on the sheet 50, and the members 140, 144 areadjusted to a desired configuration. The heater 122 is used to heat thesheet 50, preferably to a processing temperature that is less than theglass transition temperature of the thermoplastic material of the sheet50, as described above. The sheet 50 can be maintained at the processingtemperature for a predetermined period, after which the heater 122 canbe turned off. Preferably, the formed sheet 60 is at least partiallycooled in the apparatus 110. The formed sheet 60 is then removed fromthe apparatus 110.

The support members 140 can define different shapes than that shown inFIGS. 8–10. For example, as shown in FIG. 11, an apparatus 110 a caninclude one or more rod- or tube-shaped support members 140 a definingends that extend from a frame 116 a and upon which a shaper 114 a can bedisposed. The shaper 114 a can extend perpendicular to the longitudinaldirection of the support member 140 a, and the sheet 50 can be disposedon the shaper 114 a. Further, the shaper 114 a and, hence, the sheet 50can be elastically deformed to a compound contour, i.e., bent about morethan one axis. For example, as shown in FIG. 11, the shaper 114 a candefine a partial spherical surface.

As described above, the edges 68, 70 or other portions of the formedsheet 60 can be joined, for example, by consolidation joining. Further,the formed sheet 60 can be post-formed to provide additional contours orfeatures, such as bells, beads, and the like. A discussion regarding theformation of features such as bells and beads through post-forming,i.e., after the forming and/or the consolidation joining of the sheet,is provided in U.S. application Ser. No. 10/215,780, titled“Post-Forming of Thermoplastic Ducts” filed Aug. 9, 2002, which isassigned to the Assignee of the present invention and the entirety ofwhich is incorporated herein by reference. It is also appreciated thatmarks can be provided on the thermoplastic sheet, for example, toaccurately identify the location of such post-formed features or tofacilitate the manufacture or assembly of the formed sheets, as providedin the application entitled “Thermoplastic Laminate Duct.”

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. For example, it is appreciated that each of thecomponents of the described apparatuses can be formed of a variety ofmaterials such as aluminum, steel, and alloys thereof, and each of theworking surfaces of the apparatuses can include a low friction layer orrelease layer, e.g., Teflon®, registered trademark of E.I. du Pont deNemours and Company. The release layer can be a durable layer ofmaterial or a release agent that is wiped or sprayed periodically ontothe working surfaces. Therefore, it is to be understood that theinvention is not to be limited to the specific embodiments disclosed andthat modifications and other embodiments are intended to be includedwithin the scope of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

1. An apparatus for forming a thermoplastic sheet, the apparatuscomprising: a rotatable roller extending longitudinally; an elasticallyflexible shaper having first and second sides and extending from a firstedge to a second edge; and a heater configured to heat the thermoplasticsheet to a processing temperature less than a glass transitiontemperature of the thermoplastic member; wherein said shaper isconfigured to receive the thermoplastic sheet on said first side suchthat rotation of said roller in a first direction advances said firstedge at least partially around said roller with said first side directedtoward said roller and the thermoplastic sheet disposed between saidroller and said shaper, thereby bending the thermoplastic sheet.
 2. Anapparatus according to claim 1, further comprising at least onelongitudinal member extending generally parallel with said roller andconfigured to adjust inward toward the roller to bend the thermoplasticsheet to a predetermined configuration.
 3. An apparatus according toclaim 1, further comprising an index feature on said shaper, said indexfeature configured to engage the thermoplastic sheet such that theadjustment of the index feature toward said roller advances thethermoplastic sheet around said roller.
 4. An apparatus according toclaim 1, further comprising a second elastically flexible shaperconfigured to be disposed on the thermoplastic sheet such that rotationof said roller in the first direction advances the second shaper atleast partially around said roller with said second shaper disposedbetween the thermoplastic sheet and said roller, and advancement of saidsecond shaper toward said roller urges a portion of the thermoplasticsheet disposed around said roller in a direction generally outward fromsaid roller.
 5. An apparatus according to claim 1, further comprising aheat shroud at least partially enclosing said roller.
 6. An apparatusfor forming a thermoplastic sheet, the apparatus comprising: at leastthree support members defining spaces therebetween; an elasticallyflexible shaper having first and second sides and extending from a firstedge to a second edge, said shaper configured to be disposed with saidsecond side against said support members such that said shaper extendsacross the spaces between said support members; and a heater configuredto heat the thermoplastic sheet to a processing temperature less than aglass transition temperature of the thermoplastic member, wherein saidshaper is configured to receive the thermoplastic sheet on said firstside and bend partially around said support members such that thethermoplastic sheet is formed to a predetermined shape.
 7. An apparatusaccording to claim 6, wherein each support member extends in alongitudinal direction such that said support members are generallyparallel.
 8. An apparatus according to claim 7, wherein at least one ofthe support members is configured to be adjusted in a directionperpendicular to the longitudinal direction of the support members. 9.An apparatus according to claim 6, further comprising a heat shroud atleast partially enclosing said support members.
 10. An apparatusaccording to claim 1 wherein one of the edges of said shaper isconnected to said roller.
 11. An apparatus according to claim 1 whereinone of the edges of said shaper is configured to be advanced at leastabout 360° about said roller.
 12. An apparatus according to claim 1,further comprising at least two longitudinal members extending generallyparallel with said roller and configured to adjust radially inwardtoward the roller to bend the thermoplastic sheet to a predeterminedconfiguration.
 13. An apparatus according to claim 3 wherein said indexfeature on said shaper is configured to contact an edge of thethermoplastic sheet.